Double Stars
Alpha Hercules
Double and Multiple stars are stars that are bound together by gravity, and orbit around a common centre of gravity.It is believed the majority of stars in the sky are in fact this type.Many double stars can be separated by a small aperture telescope 60mm up to 100mm.I use a 100mm off-axis mask on my reflector when looking at double stars. Another type of double star is an optical double, these stars just happen to appear close together as they are on the same line of sight from us but may be hundreds of light years apart.Good seeing and high magnification are required when splitting close doubles.Double star viewing can still be carried out in moonlit or light polluted conditions providing of course you can still star hop to the desired star.
In the list below the brighter star is designated "A".Separation is in arc seconds.